Semiconductor device

ABSTRACT

A semiconductor device with a packaging circuit portion connected to a semiconductor chip therein. The semiconductor chip includes a plurality of pad electrodes, and the packaging circuit portion includes wiring connected to the pad electrodes on the semiconductor chip, mounting terminals, and a first signal path for receiving a signal output from the predetermined one of the pad electrodes and transmitting the signal to other one of the pad electrodes. The first signal path includes delay elements comparable to delays in a second signal path extending from the predetermined one of the mounting terminals to the other one of the mounting terminals through the semiconductor chip, and is disposed on a feedback path for phase comparison for synchronizing the phase of an output signal from the second signal path to the phase of an input signal to the second signal path.

INCORPORATION BY REFERENCE

The present application claims priority from Japanese applicationJP2003-385743 filed on Nov. 14, 2003, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor device having afeedback loop for internal signal synchronization to an external signal.More specifically, the invention relates to a delay setting in thefeedback loop. The invention relates to the delay time setting in thefeedback loop in a clock synchronization circuit typified by a DLL(delay-locked loop) circuit, for example, and further relates to atechnique that is effective for being applied to clock reproduction forreproducing the phase of an input clock signal for use as the phase ofan output clock signal.

Clock synchronization memories such as a synchronous DRAM have a DLLcircuit. In the DLL circuit, an external clock signal is delayed bypredetermined cycles, thereby reproducing the phase of an input clocksignal for use as the phase of an output clock signal. Then, using theclock reproduction, an output timing of read data is synchronized withthe phase of the output clock signal. The DLL circuit has the feedbackloop for clock phase control. When the phase of the input clock signalis reproduced for use as the phase of the output clock signal, a delaycircuit simulating a delay generated in an on-chip circuit configurationand a chip package should be provided for the feed back loop, and thenfeedback control of a phase difference between a feedback clock signaland a reference clock signal in the feedback loop should be exercised.In order to reproduce the phase of the input clock signal for use forthe output clock signal, it becomes necessary to consider compatibilitybetween the synchronization circuit and delay components caused byinductance components such as those of bonding pads, wires, bumpelectrodes, and leads and electrostatic capacitance components as well.In the circuit that simulates these delay components, an error from anactual delay might be generated due to the influence of variations inthe semiconductor processing technology and changes in the temperatureof the devices of the circuit. JP-A-2000-231421 discloses a techniquefor providing an off-chip driver, a clock receiver, and wiring in thefeedback loop to simulate a system clock delay.

SUMMARY OF THE INVENTION

In high-speed SRAMs for communications applications, in order toimplement a high-speed operation, it has been mainstream to mount theDLL circuit inside the SRAM. In order to achieve the high-speedoperation required by the user, there is the need for increasing theaccuracy of the DLL circuit. For this reason, the inventors of thepresent invention have studied the feedback loop of the DLL circuit soas to perform delay control with a high precision by the DLL circuit.Based on the study, the inventor has found importance of matching adelay in the feedback loop of the DLL circuit with a delay from anexternal clock input terminal to an external clock output terminal witha high precision. JP-A-2000-231421 does not clarify such importance ofmatching.

An object of the present invention is therefore to provide asemiconductor device that can match a delay in a feedback path with adelay from an external clock input terminal to an external clock outputterminal with a high precision.

The above and other objects and novel features of the present inventionwill be made clear from a description of the specification and theappended drawings.

A brief description of an overview of typical ones of the inventionsdisclosed in the present application is as in the following.

The following is a brief description of effects that can be obtainedfrom the typical ones of the inventions disclosed in the presentapplication.

-   [1] According to one aspect of the present invention, in a    semiconductor device with a packaging circuit portion connected to a    semiconductor chip,

the semiconductor chip includes a plurality of pad electrodes; and

the packaging circuit portion includes:

wiring connected to the pad electrodes on the semiconductor chip;

a plurality of mounting terminals; and

a first signal path for receiving a signal output from a predeterminedone of the pad electrodes and transmitting the signal to other one ofthe pad electrodes. The first signal path includes delay elementscomparable to a delay in the first portion of a second signal path froma predetermined one of the mounting terminals to one of the padelectrodes for input on the semiconductor chip and a delay in the secondportion of the second signal path from one of the pad electrodes foroutput on the semiconductor chip to other one of the mounting terminals,and is disposed on a feedback path for phase comparison forsynchronizing the phase of an output signal from the second signal pathto the phase of an input signal to the second signal path, the secondsignal path extending from the predetermined one of the mountingterminals to the other one of the mounting terminals through thesemiconductor chip.

According to the semiconductor device described above, the feedback pathincludes the delay elements comparable to the delay in the first portionof the second signal path from the predetermined one of the mountingterminals to the one of the pad electrodes for input on thesemiconductor chip and the delay in the second portion of the secondsignal path from the one of the pad electrodes for output on thesemiconductor chip to the other one of the mounting terminals, thesecond signal path extending from the predetermined one of the mountingterminals to the other one of the mounting terminals through thesemiconductor chip. Thus, even if there are variations in themanufacturing process and changes in temperature, the phase of an inputclock signal to one mounting terminal can be reproduced and then used asthe phase of an output clock signal from other mounting terminal. Inother words, a match between the delay in the feedback path and thedelay generated from the clock input mounting terminal to the clockoutput mounting terminal with high precision can be made.

According to a specific embodiment of the present invention, the firstsignal path is a replica circuit simulating a delay element in the firstportion and a delay element in the second portion. Further, thesemiconductor chip includes a clock synchronization circuit connected tothe first portion, the second portion, and the first signal path,respectively, and the clock synchronization circuit delays the clocksignal output from the mounting terminal on the second portion bypredetermined cycles with respect to the signal received at the mountingterminal on the first portion, for phase synchronization.

Assuming a conductor device such as a flip chip, the semiconductor chipincludes:

a semiconductor substrate;

a plurality of circuit elements formed on an element formation layer onthe semiconductor substrate; and

a plurality of pad electrodes formed on the surface of the elementformation layer and connected to predetermined ones of the circuitelements. The packaging circuit portion includes a conductive layerconnected to the predetermined ones of the pad electrodes and extendingon the element formation layer, and the mounting terminals are bumpelectrodes connected to the conductive layer. In this case, the firstsignal path includes a predetermined conductive layer for connecting thepredetermined one of the pad electrodes and the other one of the padelectrodes, and lands for the bump electrodes are formed in parts of theconductive layer.

Assuming the semiconductor device with the flip chip mounted on asingle-layer or a multi-layer wiring substrate, the semiconductor chipincludes:

a semiconductor substrate;

a plurality of circuit elements formed on an element formation layer onthe semiconductor substrate; and

a plurality of pad electrodes formed on the surface of the elementformation layer and connected to predetermined ones of the circuitelements. The packaging circuit portion includes:

a conductive layer connected to the predetermined ones of the padelectrodes and extending on the element formation layer;

bump electrodes formed over the conductive layer;

single-layer or multi-layer wiring and through holes connected to thebump electrodes; and

ball electrodes connected to predetermined ones of the single-layerwiring or the multi-layer wiring, for use as the mounting terminals. Inthis case, the first signal path includes:

a predetermined conductive layer;

the bump electrodes connected to the predetermined conductive layer; and

the single-layer or multi-layer wiring and the through holes connectedto the bump electrodes. Lands for the ball electrodes are formed inparts of the single-layer or multi-layer wiring.

-   [2] A semiconductor device according to a second aspect of the    present invention includes:

a semiconductor chip; and

a packaging circuit portion including external connecting terminals formounting and wiring paths for connecting the external connectingterminals to corresponding terminals on the semiconductor chip, formedthereon. The packaging circuit portion includes a specific delay pathfor receiving a signal from the semiconductor chip and outputting thesignal to the semiconductor chip. The specific delay path does notreceive the signal from any of the external connecting terminals noroutput the signal to any of the external connecting terminals. Thespecific delay path is disposed on a feedback path for phase comparison,for synchronizing the phase of an output signal from the predeterminedone of the external connecting terminals to the phase of an input signalto other predetermined one of the external connecting terminals.

According to the semiconductor device described above, the specificdelay path is caused to simulate predetermined signal propagation delaysbetween the external connecting terminals of the packaging circuitportion and the semiconductor chip, and the specific delay path isincluded in the feedback path for phase comparison. Thus, when the phaseof an output signal from the predetermined one of the externalconnecting terminals is synchronized to the phase of an input signal toother predetermined one of the external connecting terminals, thecharacteristics of the specific delay path also track variations in thepredetermined signal propagation delays caused by variations in themanufacturing process and changes in temperature. A match between thedelay in the feedback path and the delay generated from the clock inputmounting terminal to the clock output mounting terminal with highprecision therefore becomes possible. Accordingly, synchronization ofthe phase of an output signal from the predetermined one of the externalconnecting terminals to the phase of an input signal to otherpredetermined one of the external connecting terminals with highprecision becomes possible.

According to a specific embodiment of the present invention, thespecific delay path is a dummy signal path for simulating the delaycharacteristics of predetermined signal paths on the packaging circuitportion. The dummy signal path simulates a clock propagation path from aclock input terminal as one of the external connecting terminals to thesemiconductor chip and a clock propagation path from the semiconductorchip to a clock output terminal as other one of the external connectingterminals. The semiconductor chip further includes a delay-locked loopcircuit connected to the dummy signal path and both of the clockpropagation paths, and the delay-locked loop performs phasesynchronization for delaying the phase of a clock signal output from theother one of the external connecting terminals by predetermined cycleswith respect to a clock signal received at one of the externalconnecting terminals.

Assuming the conductor device such as the flip chip, the packagingcircuit portion includes a conductive layer connected to pad electrodeson the semiconductor chip and extending on the semiconductor chip; and

bump electrodes connected to the conductive layer, for use as theexternal connecting terminals.

Assuming the semiconductor device with the flip chip mounted on thesingle-layer or multi-layer wiring substrate, the packaging circuitportion includes:

a conductive layer connected to pad electrodes on the semiconductor chipand extending on the semiconductor chip;

bump electrodes connected to the conductive layer;

single-layer or multi-layer wiring and through holes connected to thebump electrodes; and

ball electrodes connected to predetermined single-layer or multi-layerwiring, for use as the external connecting terminals.

-   [3] According to an aspect centering on a delay-locked loop circuit,    a semiconductor device of the present invention includes:

a semiconductor chip having the delay-locked loop circuit formed on asemiconductor substrate: and a packaging circuit portion having externalconnecting terminals for mounting and wiring paths for connectingterminals of the semiconductor chip to corresponding ones of theexternal connecting terminals, formed thereon. The delay-locked loopcircuit reproduces the phase of an input clock signal supplied from oneof the external connecting terminals, for output as the phase of anoutput clock signal from other one of the external terminals, based on aresult of phase comparison between the input clock signal and a delayedclock signal obtained by delaying the input clock signal by a delaycircuit. The delay circuit is formed on the packaging circuit portion,and constitutes a replica circuit for simulating a delay element fromthe one of the external connecting terminals for receiving the clocksignal to the semiconductor chip and a delay element from thesemiconductor chip to the other one of external connecting terminals foroutputting the output clock signal.

Other objects, features and advantages of the invention will becomeapparent from the following description of the embodiments of theinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a configuration of an SRAM, which is a semiconductordevice according to the present invention, centering on a DLL circuit;

FIG. 2 is a block diagram illustrating a data processing system usingthe SRAM in FIG. 1;

FIG. 3 is a timing chart illustrating timings of a clock reproducingoperation or a clock synchronizing operation using the DLL circuit;

FIG. 4 is a plan view illustrating planar configurations of surfaces ofpad electrodes on an SRAM chip in the form of a structure such as a flipchip;

FIG. 5 is a sectional view illustrating a vertical sectional structureof the SRAM so that clock synchronization paths and the like are shown;

FIG. 6 is a sectional view illustrating a vertical sectional structureof the SRAM so that a feedback path FBR2 and the like are shown;

FIG. 7 is a plan view illustrating wiring paths inside a conductivelayer L1 in the same direction as FIG. 4;

FIG. 8 is a plan view illustrating wiring paths inside a conductivelayer L4 in the same direction as FIG. 4;

FIG. 9 is an explanatory diagram two-dimensionally showing arrangementof paths CR1, CR2, and DR3; and

FIG. 10 is a vertical sectional view of the SRAM constituted as the flipchip.

DESCRIPTION OF THE EMBODIMENTS

FIG. 2 illustrates a data processing system using an SRAM (static randomaccess memory) 1 as an example of a semiconductor device according tothe present invention. The data processing system shown in FIG. 2includes the SRAM 1, a communication controller (TCTRL) 2 constitutingpart of a router, for example, and a CPU (central processing unit) 3,which are shown typically. These units are connected in common to asystem bus (SBUS) 4. The SRAM 1 has a clock reproducing function ofreproducing the phase of an input clock for use as the phase of anoutput clock. The input clock is a clock signal C_CLK such as a systemclock signal output from the CPU 3, and the output clock is a clocksignal CQ_CLK, for example. The clock signal CQ_CLK is supplied to theCPU 3 and the TCTRL 2. The SRAM 1 is synchronized with the clock signalC_CLK. The CPU 3 and the TCTRL 2 can be informed of determination ofread data on the system bus 4 or output of the read data to the systembus 4 in synchronization with a change in the clock signal CQ_CLK. TheSRAM 1 includes a DLL circuit for fulfilling a clock reproducingfunction.

FIG. 1 illustrates a configuration of the SRAM 1 centering on the DLLcircuit. Though no particular limitation is imposed on the SRAM 1, theSRAM 1 is constituted from an SRAM chip 11 as a semiconductor chip(pellet) and a packaging circuit portion (hereinafter also referred toas a package) 10 connected to the SRAM chip 11. Though details of thepackage 10 will be described hereinafter, a configuration for face downmounting is assumed herein. The SRAM chip 11 includes a plurality of padelectrodes 13A to 13J typified as external terminals. The package 10includes external connecting terminals 14A to 14H as a plurality ofmounting terminals for mounting the SRAM 1 on a mounting board (notshown). Reference characters D, K and /K, C and /C, Q, and CQ and /CQindicated in the external connecting terminals 14A to 14G, respectively,denote a data input terminal, data input clock terminals, data outputclock terminals, a data output terminal, and clock input terminals,respectively. A symbol/appended to a signal indicates that the signal isan inverted signal.

On the SRAM chip 11, a memory array 20, a DLL circuit 21, input buffers22A to 22E, 22J, and output buffers 23F to 23I, which are showntypically, are formed.

Though a specific illustration of the memory array 20 is omitted, thememory array 20 includes a lot of static memory cells arranged in amatrix. Selection terminals of the memory cells are connected tocorresponding word lines, and data input and output terminals of thememory cells are connected to corresponding bit lines. The bit lines areselectively conducted to common data lines through a column switchcircuit, for activation. A sense amplifier and a write amplifier areconnected to the common data lines. The sense amplifier senses data readfrom a memory cell and supplies the read data to the output buffer 23F.Write data is supplied from the input buffer 22A to the write amplifier.Selection of a word line and a column switch is performed using a signalthat decodes an address signal input to an address input buffer of whichillustration is omitted. Illustration of input paths for a strobe signaland the address signal for chip selection is omitted. Read and writeoperation controls are performed based on a timing signal generated by atiming controller of which illustration is omitted. The DLL circuit 21herein defines a data output timing during the read operation control bythe timing controller not shown.

The DLL circuit 21 includes variable delay circuits (VCD) 25 and 26 anda phase comparator 27, which are typically shown. The clock signal C_CLKfrom the external connecting terminal 14D is transmitted to one variabledelay circuit 25, and is delayed according to a comparison result signalScmp indicating the result of a comparison output from the phasecomparator 27. The delayed clock signal is transmitted to the externalconnecting terminal 14H and output as the clock signal CQ_CLK. A signalpath from the external connecting terminal 14D to the externalconnecting terminal 14H is positioned as a second signal path. The phasecomparator 27 detects a phase difference of a feedback clock signalFB_CLK from a reference clock signal ref_CLK. The reference clock signalref_CLK is used as a clock for an input node ND of the variable delaycircuit (VCD) 25. The feedback clock signal FB_CLK propagates throughfeedback paths FBR1, FBR2, and FBR3 from the input node ND. The feedbackpath FBR1 indicates the path from the input node ND to pad electrode13I, the feedback path FBR2 indicates the path from the pad electrode13I to pad electrode 13J, and feedback path FEBR3 indicates the pathfrom the pad electrode 13J to the input terminal of the phase comparator27 through the variable delay circuit (VCD) 26. The feedback path FBR 2is positioned as a first signal path.

The feedback paths FBR1 and FBR3 are constituted as a replica circuitwithin the chip (an on-chip replica circuit) simulating delay elementsor delay components in a path from the pad electrode 13D to the padelectrode 13H through the VCD 25 inside the SRAM chip 11. In short, thebuffer 23I is positioned as a replica buffer corresponding to the buffer23H, and the buffer 22J is positioned as a replica buffer correspondingto the buffer 22D. The VCD 26 has the same circuit configuration as theVCD 25, and is positioned as a replica circuit subject to the samevariable delay control as the VCD 25 according to the comparison resultsignal Scmp. Wiring resistances, parasitic capacitances that exist inthe wiring, and inductance components in the wiring of the feedbackpaths FBR1 and FBR3 are set to be comparable to those in the path fromthe pad electrode 13D to the pad electrode 13H through the VCD 25.

The feedback path FBR2 is constituted as a replica circuit (anon-package replica circuit) simulating delay elements or delaycomponents in a path from the external connecting terminal 14D to thepad electrode 13D on the package 10 (a first portion of the secondsignal path) and delay elements or delay components in a path from thepad electrode 13H to the external connecting terminal 14H (a secondportion of the second signal path). The delay elements or the delaycomponents correctively refer to wiring resistances, parasiticcapacitances in wiring, and inductance components in the wiring. When adelay time caused by the delay elements in the path from the externalconnecting terminal 14D to the pad electrode 13D (first portion of thesecond signal path) is indicated by td1, and a delay time caused by thedelay elements in the path from the pad electrode 13H to the externalconnecting terminal 14H (second portion of the second signal path) isindicated by td2, a delay time td3 in the feedback path (first signalpath) FBR 2 is indicated by td3=td1+td2. Incidentally, elements d0 to d9drawn as cylindrical figures on the wiring for the packaging circuitportion 10 represent delay elements caused by the wiring resistances inthese wiring, parasitic capacitances in the wiring, and inductances inthe wiring. For, example, the element d3 represents the delay elementsthat exit in the wiring between the external connecting terminal 14D andthe pad electrode 13D. The element d5 represents the delay elements thatexist between the pad electrode 13H and the external connecting terminal14H. The elements d8 and d9 indicate the delay elements that exist inthe feedback path FBR2 (first signal path) between the pad electrode 13Iand the pad electrode 13J. Thus, the delay time of the delay element d3is indicated by td1, and the delay time of the delay element d5 isindicated by td2. The delay time of the delay elements d8 and d9 isindicated by td3, which is equal to the sum of td1 and td2.

By giving the delay time caused by the on-chip replica circuitconstituted from the feedback loop FBR1 and FBR3 and the delay timecaused by the on-package replica circuit constituted from the feedbackpath FBR2 to the feedback clock signal FB_CLK, the phase of thereference clock signal ref_CLK is aligned with the phase of the feedbackclock signal FB_CLK. The phase of the clock signal C_CLK input to theexternal connecting terminal 14D is thereby reproduced to be used forthe output clock signal CQ_CLK of the external connecting terminal 14H,and the rise timing of the clock signal C_CLK is matched orsubstantially matched with the rise timing of the clock signal CQ_CLK.The number of clock cycles from input of the clock signal C_CLK to thereproduction for the clock signal CQ_CLK is determined by the number ofcycles of the clock signal C_CLK set to be the delays by the variabledelay circuits 25 and 26 when the phase of the reference clock signalref_CLK has matched the phase of the feedback clock signal FB_CLK. Totake an example, assume that the clock signal CQ_CLK appears at theexternal connecting terminal 14H after two cycles of the clock signalC_CLK from input of the clock signal C_CLK to the external connectingterminal 14D. An input to the output buffer 23H is used for outputcontrol of the output buffer 23F. Data output from the output buffer 23Fis thus output from the pad 13F at the same timing as that for theoutput clock signal OUT_CLK output from the pad 13H. The delay timecaused by the delay elements that exist from the pad electrode 13F tothe external connecting electrode 14F is set approximately to td2, sothat a change in data output from the external connecting terminal 14Fis generated in synchronization with the timing of a change in the clocksignal output from the external connecting terminal 14H.

FIG. 3 illustrates timings of a clock reproducing operation or a clocksynchronizing operation using the DLL circuit 21. When the clock signalC_CLK rises at the external connecting terminal 14D at time t0, a clocksignal IN1_CLK rises at the pad electrode 13D after a delay time td1.Then, sequential delays occur, and in a clock output system, thereference clock signal ref_CLK rises, the clock signal OUT_CLK rises atthe pad electrode 13H, and the clock signal CQ_CLK rises at the externalconnecting terminal 14H. In the feedback path, a clock signal DLLo_CLKrises at the pad electrode 13I, a clock signal DLLi_CLK rises at the padelectrode 13J, and the feedback clock signal FB_CLK rises. At the startof the operation, the phase of the reference clock signal ref_CLK is notaligned with the phase of the feedback clock signal FB_CLK. Thus, delaytime control is performed by the variable delay circuits 25 and 26 so asto reduce a difference in the phases. The phase of the feedback clocksignal FB_CLK is thus aligned with the phase of the reference clocksignal ref_CLK. In this state, the feedback clock signal FB_CLK hasdelays in the feedback paths FBR1, FBR2, and FBR3 with respect to thereference clock signal ref_CLK. The delays become the sum of a delaycaused by the on-chip replica circuit and a delay caused by theon-package replica circuit, which corresponds to the delay time requiredfor a change in the clock signal at the external connecting terminal 14Dto propagate to the external connecting terminal 14H. Accordingly, thephase of the clock signal C_CLK input to the external connectingterminal 14D is reproduced to be used for the clock CQ_CLK output fromthe external connecting terminal 14H. Likewise, read data having thesame phase as the clock signal C_CLK is output from the externalconnecting terminal 14F.

As described above, in order to bring the delay in the path from theinput terminal 14D for the clock signal C_CLK to the output terminal 14Hfor the clock signal CQ_CLK closer to the sum of the delays in thefeedback paths FBR1, FBR2, and FBR3, the on-chip replica circuit havingsubstantially the same circuit configuration is used for the delaygenerated in the circuit configuration on the SRAM chip 11, and theon-package replica circuit using dummy wiring is fabricated for thedelay generated on the package 10. An example of the on-package replicacircuit will be described below.

FIG. 4 shows planar configurations of the surfaces of the pad electrodeson the SRAM chip 11 in the form of a structure such as a flip chip. Thepad electrodes such as the pad electrode 13H are illustrated as smallsquares and disposed in the central portions of the chip. On the surfaceof the SRAM chip 11, the pad electrodes (collectively indicated byreference numeral 13) are exposed. Then, the surface is covered by aninsulating film. A lot of comparatively large bump electrodes(collectively indicated by reference numeral 34) are disposed over awide range in the form of concentric circles, and the pad electrodes 13and the bump electrodes 34 corresponding to one another are connectedvia relocation wiring (collectively indicated by reference numeral 32),thereby forming the flip-flop structure. Small inner circles of theconcentric circles shown as symbols for the bump electrodes 34 denotethe bump electrodes 34, and large outer circles denote bump lands(collectively indicated by reference numeral 33) for mounting the bumpelectrodes 34, formed at the ends of the relocation wiring 32. A blackcircle with CQ denotes the bump electrode connected to the pad electrode13H, a black circle with /CQ denotes the bump electrode connected to thepad electrode 13G, A black circle with DLLo denotes the bump electrodeconnected to the pad electrode 13I, a black circle with DLLi denotes thebump electrode connected to the pad electrode 13J, a black circle with Cdenotes the bump electrode connected to the pad electrode 13D, and ablack circle with /C denotes the bump electrode connected to the padelectrode 13E.

FIG. 5 illustrates a vertical sectional structure of an SRAM so thatclock synchronization paths are shown. The section in FIG. 5 is takenroughly along a direction A in FIG. 4. The package 10 for the SRAM chip11 is constituted from a face down mounting structure 10A and amulti-layer wiring substrate 10B of a flip chip.

Circuit elements for constituting the SRAM are formed on thesemiconductor substrate made of a material such as monocrystallinesilicone, and the pad electrodes 13 connected to the circuit elementsare exposed on the surface of the SRAM chip 11. Like bonding pads, thepad electrodes 13 are disposed in a small area at high density. One endsof the relocation wiring 32 are coupled to the pad electrodes 13, andthe other ends are distributed on the chip. The bump electrodes 34 arearranged like an array (in an area-array form) in the bump land 33 atthe other ends of the relocation wiring, and the bump electrodes 34arranged like the area array are exposed from an insulating film 35.With this arrangement, the bump electrodes 34 are arranged at largerspacings than the pad electrodes 13, thereby facilitating face downmounting.

A multi-layer wiring substrate 10B includes four conductive layers L1 toL4 insulated to one another. The conductive layer L3 constitutes a powersupply plane to which a power supply voltage VDD is fed. The conductivelayer L2 constitutes a ground plane to which a ground potential VSS forthe circuit is supplied. The conductive layers L1 and L4 are used aswiring layers. Connection between the conductive layers L1 and L4 isperformed via through holes 40. The conductive layer L1 is connected topredetermined ones of the bump electrodes 34 through their bump lands41. The conductive layer L4 is connected to predetermined ones of theball electrodes 43 through their ball lands 42.

In the example in FIG. 5, the ball electrodes 43 constitute the externalconnecting electrodes (collectively indicated by reference numeral 14)such as the external connecting electrode 14D. Referring to FIG. 5, theball electrode 43 with CQ constitutes the external connecting terminal14H, the ball electrode 43 with C constitutes the external connectingelectrode 14D, and the ball electrode 43 with /C constitutes theexternal connecting terminal 14E. The pad electrode 13 with CQconstitutes the pad electrode 13H, while the pad electrode 13 with Cconstitutes the pad electrode 13D. A plurality of pad electrodes 13 areformed on the SRAM chip 11. An element formation layer (not shown) isformed on the surface of the SRAM chip 11 where the pad electrodes areformed.

In FIG. 5, a path CR1 from the external connecting terminal 14D(constituted from the ball electrode 43 with C) to the pad electrode 13D(constituted from the pad electrode 13 with C) (or the first portion ofthe second signal path) and a path CR2 from the pad electrode 13H(constituted from the pad electrode 13 with CQ) to the externalconnecting terminal 14H (constituted from the ball electrode 43 with CQ)(or the second portion of the second signal path) are shown as the clocksynchronization paths.

FIG. 6 illustrates a vertical sectional structure of the SRAM so thatthe feedback path FBR2 is shown. The section in FIG. 6 is taken roughlyalong a direction B in FIG. 4. Referring to FIG. 6, a path DR3 from thepad electrode 13I (the pad electrode 13 with DLLo) to the pad electrode13J (the pad electrode 13 with DLLi) (or the first signal path) is shownas the feedback path FBR2.

The path DR3 (FBR2) in FIG. 6 becomes the replica circuit that simulatesthe path which is the sum of the paths CR1 and CR2 in FIG. 5, and thelength of wiring and wiring elements of the path DR3 are so designed tobe the same as those of the paths CR1 and CR2 as much as possible. Thepath DR3 (FBR2) is not connected to a ball electrode 43, but is designedto pass through dummy lands 42D.

FIG. 7 illustrates wiring paths inside the conductive layer L1 in thesame direction as FIG. 4. Likewise, FIG. 8 illustrates wiring pathsinside the conductive layer L4 in the same direction as FIG. 4. The padelectrode with C shown in FIG. 4, for example, is electrically conductedfrom the bump electrode indicated by reference character C in FIG. 7 tothe conductive layer L4 constituting the path CR1, electricallyconducted to the conductive layer L4 constituting the path CR1 in FIG.8, and then connected to the ball electrode with C BALL. FIG. 9two-dimensionally shows arrangement of the paths CR1, CR2, and DR3. FromFIG. 9, it can be seen that the wiring length of the path DR3 is alsosimulated and formed to be comparable to the sum of the wiring lengthsof the paths CR1 and CR2. Incidentally, in FIG. 9, CQ-BALL and C-BALLdenote the ball electrodes 43, CQ-PAD, C-PAD, DLLo-PAD and DLLi-PADdenote the pad electrodes 13, and WPP-BMP denote the bump electrodes 34.

FIG. 10 illustrates a vertical sectional structure of the semiconductordevice when the package 10 is constituted only from the face downmounting structure 10A of a flip chip. In short, the SRAM 1 in FIG. 10is constituted as the flip chip. In this example, the bump electrodes 13are associated with the external connecting terminals 14 in FIG. 1, andare used as mounting terminals. Referring to FIG. 10, a clock input pathfrom the external connecting terminal 14D to the pad electrode 13D isshown as a path from a bump electrode 34 a to relocation wiring 32 athrough a bump land 33 a. A clock output path from the pad electrode 13Hto the external connecting terminal 14H is shown as a path fromrelocation wiring 32 b to a bump electrode 34 b through a bump land 33b. Referring to FIG. 10, the feedback path FBR2 in FIG. 1 is shown as apath from the pad electrode 13I to the pad electrode 13J throughrelocation wiring 32 c, a bump land 33 c, and relocation wiring 32 d.This path simulates the delay elements in the clock input path and theclock output path. The feedback path FBR2 uses the comparatively longbump land 33 c for simulating the bump electrodes 34 a and 34 b. In theconfiguration in FIG. 10, a package delay caused by the multi-layerwiring substrate does not need to be considered. Thus, a delay mismatchis all the more reduced.

According to the SRAM 1 described above, due to the on-package replicacircuit, the feedback path FBR3 for clock synchronization having a goodmatch with the components of a package delay generated from resistivecomponents, inductance components and electrostatic capacitancecomponents caused by the conductive layers L1 and L4, bump electrodes 13and relocation wiring can be configured. The DLL circuit 21 with highprecision, which has a less clock synchronization mismatch resultingfrom variations in the manufacturing process and changes in temperaturecan be implemented.

As described above, by adopting the DLL circuit 21 for the SRAM, thehigh-speed clock synchronization of the SRAM becomes possible. The SRAMcan be thereby made suitable for high-speed access.

The foregoing description was specifically directed to the inventionmade by the inventor of the present invention, in connection with theembodiment. The present invention, however, is not limited to thisembodiment alone. Various changes and modifications are possible withinthe spirit and scope of the invention.

The semiconductor device is not limited to the SRAM, and may be otherclock synchronization memory such as a synchronous DRAM. Further, thesemiconductor device may be a data processing LSI circuit on asystem-on-chip or a microcomputer. The wiring substrate used forpackaging is not limited to the multi-layer wiring substrate, and may bea single-layer wiring substrate. The semiconductor integrated circuitmounted on the semiconductor device is not limited to one and may be ofa multi-chip structure. The semiconductor device of the presentinvention can be applied to various data processing systems other than acommunication system such as a router.

It should be further understood by those skilled in the art thatalthough the foregoing description has been made on embodiments of theinvention, the invention is not limited thereto and various changes andmodifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

1. A semiconductor device with a packaging circuit portion connected toa semiconductor chip, wherein the semiconductor chip includes aplurality of pad electrodes; the packaging circuit portion includes:wiring connected to the pad electrodes on the semiconductor chip; aplurality of mounting terminals; and a first signal path for receiving asignal output from a predetermined one of the pad electrodes andtransmitting the signal to other one of the pad electrodes; saidsemiconductor device includes a second signal path from a predeterminedone of the mounting terminals to other one of the mounting terminal viathe semiconductor chip, and the first signal path includes delayelements comparable to a delay in a first portion of the second signalpath from the predetermined mounting terminal to one of the padelectrodes for input on the semiconductor chip and a delay in a secondportion of the second signal path from one of the pad electrodes foroutput on the semiconductor chip to other one of the mounting terminals,and is disposed on a feedback path for phase comparison forsynchronizing a phase of an output signal from the second signal path toa phase of an input signal to the second signal path, the second signalpath extending from the predetermined one of the mounting terminals tothe other one of the mounting terminals through the semiconductor chip.2. The semiconductor device according to claim 1, wherein the firstsignal path is a replica circuit simulating a delay element in the firstportion and a delay element in the second portion.
 3. The semiconductordevice according to claim 2, wherein the semiconductor chip includes aclock synchronization circuit connected to the first portion, the secondportion, and the first signal path, respectively; and the clocksynchronization circuit delays the clock signal output from the mountingterminal on the second portion by predetermined cycles with respect tothe signal received at the mounting terminal on the first portion, forphase synchronization.
 4. The semiconductor device according to claim 3,wherein the semiconductor chip includes: a semiconductor substrate; aplurality of circuit elements, formed on an element formation layer onthe semiconductor substrate; and a plurality of pad electrodes formed ona surface of the element formation layer and connected to predeterminedones of the circuit elements; and the packaging circuit portion includesa conductive layer connected to the predetermined ones of the padelectrodes and extending on the element formation layer, the mountingterminals are bump electrodes connected to the conductive layer, and thesemiconductor device is configured as a flip chip.
 5. The semiconductordevice according to claim 4, wherein the first signal path comprises apredetermined conductive layer for connecting the predetermined one ofthe pad electrodes and the other one of the pad electrodes, and landsfor the bump electrodes are formed in parts of the conductive layer. 6.The semiconductor device according to claim 3, wherein the semiconductorchip includes: a semiconductor substrate; a plurality of circuitelements, formed on an element formation layer on the semiconductorsubstrate; and a plurality of pad electrodes formed on a surface of theelement formation layer and connected to predetermined ones of thecircuit elements; and the packaging circuit portion includes: aconductive layer connected to the predetermined ones of the padelectrodes and extending on the element formation layer; bump electrodesformed over the conductive layer; single-layer or multi-layer wiring andthrough holes connected to the bump electrodes; and ball electrodesconnected to predetermined ones of the single-layer wiring or themulti-layer wiring, for use as the mounting terminals.
 7. Thesemiconductor device according to claim 6, wherein the first signal pathcomprises: a predetermined conductive layer; the bump electrodesconnected to the predetermined conductive layer; and the single-layer ormulti-layer wiring and the through holes connected to the bumpelectrodes; and lands for the ball electrodes are formed in parts of thesingle-layer or multi-layer wiring.